Whey is a liquid by-product of cheesemaking processes that provides a source of high quality protein for foods, cosmetics, and other products. Whey protein from cow's milk is actually a collection of different proteins that primarily include β-lactoglobulin (β-Lg), and α-lactalbumin (α-La), as well as glycomacropepties (GMPs) cleaved from the native casein proteins in the milk that coagulate into the cheese curd. While β-Lg has the greatest wt. % in cow's milk, this protein has a much lower concentration or is absent in human milk and can be more difficult to digest than α-La. Efforts have been made to reduce the high concentration of β-Lg in whey protein from cow's milk and bring the relative concentration of β-Lg to α-La closer to that of human milk.
These efforts have included contacting the whey protein with resins that selectively absorb or attach one or more of the whey proteins. These separation processes may include passing the native whey protein over a column of resin beads that selectively capture one or more of the protein components in the whey. Unfortunately, there have been significant challenges in developing resin materials that selectively bind α-La or β-Lg that do not capture significant amounts of the other. There have also been challenges releasing the bound proteins from the resin once the whey has passed through the column. Processes and resins have also been developed for the selective binding of GMPs, but these resins do not substantially alter the relative concentration of β-Lg to α-La, which is still heavily tilted towards β-Lg in bovine whey.
Additional efforts to separate and purify native whey include the addition of one or more chemical elements to whey that selective precipitate one or more of the proteins. Examples of these processes include the addition of ferric chloride to the whey under tightly controlled temperature and pH conditions to precipitate β-Lg. Like the resin separation techniques, there have been problems selectively precipitating the β-Lg without also precipitating significant amounts of α-La. Furthermore, removal of the precipitation salts on a commercial scale adversely impacts the economics of purifying bovine whey that is intended for human consumption.
Still other approaches have used targeted enzymatic hydrolysis to denature one or more of the whey proteins. There remains significant unpredictability in the selection of—among other factors—the enzymes, temperature, reaction time, and acidity when targeting a specific whey protein for hydrolysis without also hydrolyzing significant amounts of other proteins. In addition, small protein hydrolysates made of just one or a few amino acids (i.e., oligopeptides) often create bitter flavors and brothy solutions that have a very disagreeable taste for the average consumer.
There remains a need for processes and systems that can increase the concentration of α-La from sources of native whey such as cow's milk and sweet whey. There also remains a need for purified whey compositions with increased concentrations of α-La and reduced concentrations of β-Lg and/or GMPs that can be produced economically on a commercial scale and that are palatable to most consumers. These and other challenges are address in the present application.